6.8-stable patches

[thirdparty/kernel/stable-queue.git] / queue-6.8 / nouveau-fix-instmem-race-condition-around-ptr-stores.patch

diff --git a/queue-6.8/nouveau-fix-instmem-race-condition-around-ptr-stores.patch b/queue-6.8/nouveau-fix-instmem-race-condition-around-ptr-stores.patch
new file mode 100644 (file)
index 0000000..efd67dc
--- /dev/null
+++ b/queue-6.8/nouveau-fix-instmem-race-condition-around-ptr-stores.patch
@@ -0,0 +1,96 @@
+From fff1386cc889d8fb4089d285f883f8cba62d82ce Mon Sep 17 00:00:00 2001
+From: Dave Airlie <airlied@redhat.com>
+Date: Thu, 11 Apr 2024 11:15:09 +1000
+Subject: nouveau: fix instmem race condition around ptr stores
+
+From: Dave Airlie <airlied@redhat.com>
+
+commit fff1386cc889d8fb4089d285f883f8cba62d82ce upstream.
+
+Running a lot of VK CTS in parallel against nouveau, once every
+few hours you might see something like this crash.
+
+BUG: kernel NULL pointer dereference, address: 0000000000000008
+PGD 8000000114e6e067 P4D 8000000114e6e067 PUD 109046067 PMD 0
+Oops: 0000 [#1] PREEMPT SMP PTI
+CPU: 7 PID: 53891 Comm: deqp-vk Not tainted 6.8.0-rc6+ #27
+Hardware name: Gigabyte Technology Co., Ltd. Z390 I AORUS PRO WIFI/Z390 I AORUS PRO WIFI-CF, BIOS F8 11/05/2021
+RIP: 0010:gp100_vmm_pgt_mem+0xe3/0x180 [nouveau]
+Code: c7 48 01 c8 49 89 45 58 85 d2 0f 84 95 00 00 00 41 0f b7 46 12 49 8b 7e 08 89 da 42 8d 2c f8 48 8b 47 08 41 83 c7 01 48 89 ee <48> 8b 40 08 ff d0 0f 1f 00 49 8b 7e 08 48 89 d9 48 8d 75 04 48 c1
+RSP: 0000:ffffac20c5857838 EFLAGS: 00010202
+RAX: 0000000000000000 RBX: 00000000004d8001 RCX: 0000000000000001
+RDX: 00000000004d8001 RSI: 00000000000006d8 RDI: ffffa07afe332180
+RBP: 00000000000006d8 R08: ffffac20c5857ad0 R09: 0000000000ffff10
+R10: 0000000000000001 R11: ffffa07af27e2de0 R12: 000000000000001c
+R13: ffffac20c5857ad0 R14: ffffa07a96fe9040 R15: 000000000000001c
+FS:  00007fe395eed7c0(0000) GS:ffffa07e2c980000(0000) knlGS:0000000000000000
+CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+CR2: 0000000000000008 CR3: 000000011febe001 CR4: 00000000003706f0
+DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+Call Trace:
+
+...
+
+ ? gp100_vmm_pgt_mem+0xe3/0x180 [nouveau]
+ ? gp100_vmm_pgt_mem+0x37/0x180 [nouveau]
+ nvkm_vmm_iter+0x351/0xa20 [nouveau]
+ ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau]
+ ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
+ ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
+ ? __lock_acquire+0x3ed/0x2170
+ ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
+ nvkm_vmm_ptes_get_map+0xc2/0x100 [nouveau]
+ ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau]
+ ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
+ nvkm_vmm_map_locked+0x224/0x3a0 [nouveau]
+
+Adding any sort of useful debug usually makes it go away, so I hand
+wrote the function in a line, and debugged the asm.
+
+Every so often pt->memory->ptrs is NULL. This ptrs ptr is set in
+the nv50_instobj_acquire called from nvkm_kmap.
+
+If Thread A and Thread B both get to nv50_instobj_acquire around
+the same time, and Thread A hits the refcount_set line, and in
+lockstep thread B succeeds at refcount_inc_not_zero, there is a
+chance the ptrs value won't have been stored since refcount_set
+is unordered. Force a memory barrier here, I picked smp_mb, since
+we want it on all CPUs and it's write followed by a read.
+
+v2: use paired smp_rmb/smp_wmb.
+
+Cc: <stable@vger.kernel.org>
+Fixes: be55287aa5ba ("drm/nouveau/imem/nv50: embed nvkm_instobj directly into nv04_instobj")
+Signed-off-by: Dave Airlie <airlied@redhat.com>
+Signed-off-by: Danilo Krummrich <dakr@redhat.com>
+Link: https://patchwork.freedesktop.org/patch/msgid/20240411011510.2546857-1-airlied@gmail.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/gpu/drm/nouveau/nvkm/subdev/instmem/nv50.c |    7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+--- a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/nv50.c
++++ b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/nv50.c
+@@ -222,8 +222,11 @@ nv50_instobj_acquire(struct nvkm_memory
+       void __iomem *map = NULL;
+ 
+       /* Already mapped? */
+-      if (refcount_inc_not_zero(&iobj->maps))
++      if (refcount_inc_not_zero(&iobj->maps)) {
++              /* read barrier match the wmb on refcount set */
++              smp_rmb();
+               return iobj->map;
++      }
+ 
+       /* Take the lock, and re-check that another thread hasn't
+        * already mapped the object in the meantime.
+@@ -250,6 +253,8 @@ nv50_instobj_acquire(struct nvkm_memory
+                       iobj->base.memory.ptrs = &nv50_instobj_fast;
+               else
+                       iobj->base.memory.ptrs = &nv50_instobj_slow;
++              /* barrier to ensure the ptrs are written before refcount is set */
++              smp_wmb();
+               refcount_set(&iobj->maps, 1);
+       }
+